1. Field of the Invention
The present invention relates to a plasma display panel (PDP), and in particular, to a plasma display panel which can be easily constructed with a finely detailed pitch of picture elements which is essential to provide numerous picture elements with a fine resolution and which can be used as a large-sized display panel.
2. Description of the Prior Art
The basic structure of a plasma display panel, as shown in FIG. 1, comprises a front substrate 1, on which anode electrodes 3 are formed; a back substrate 2 on which cathode electrodes 4 are formed; and barriers 5 disposed between the foregoing insulating substrates. Namely, the plasma display panel is constituted of a group of cathode electrodes and a group of anode electrodes, disposed perpendicular to one another, and the black barriers (5) which are disposed between the two groups of the electrodes so as to prevent cross-talk of light between the electrodes and provide sharply-defined pictures. A rare gas is enclosed within the electrodes and each intersection of the electrodes formed between the upper and lower substrates corresponds to one picture element. A voltage of 100V or greater is applied between the two electrodes and the gas is caused to undergo a glow discharge. The light generated in the glow discharge is used to form the display. The barriers have a configuration of about 100 .mu.mm in width and at least 100 .mu.m in height and, in display panels of A4 size, about 640 barriers are formed. Conventionally, these barriers have been formed by forming a pattern using a paste mixture consisting of ceramic powder, organic binder and solvent, etc., by a thick printing process, drying and firing. Also, cathode electrodes have been formed by printing a paste of a mixture consisting of electrode powder, organic binder and solvent, etc.
However, the conventional barriers have the following types of problems.
(1) The conventional barriers have been formed by the thick film printing in which the thickness obtained by one printing operation is at most ten-odd microns and the printing process should be repeated at least about ten times until the required height of at least 100 .mu.mm is obtained. Therefore, alignment in each printing operation is very difficult and the yield of the resultant product is low.
(2) Since the conventional barriers have been fabricated by repetition of the thick film printing, both the minimum line width and the narrowest spacing between the barriers are on the order of about 100 .mu.mm.
Further, referring to the shape of the barriers in the vertical direction, the ratio of the half-width to the base width (line width at the half-height of the barrier to the line width at the base of each barrier) is on the order of 0.5. This is disadvantageous in achieving very fine resolution. When the plasma display panel is used for a color picture, fluorescent materials of the three primary colors, i.e., red, green, and blue are applied between the barriers. Because the three primary color sections become one picture element, coarse pictures having a picture element of about 600 .mu.mm square are produced.
(3) Since the barriers are produced by a thick film printing method using a stainless screen, the printed area is limited by the size of the screen. It is therefore very difficult to obtain a large-sized display of greater than A4 size. Therefore, a new method of forming barriers has been demanded.
Also, in a plasma display, when the electric discharge occurs within the electric discharge space, the atoms of gas are excited by electrons, and light is produced when these excited atoms revert to the ground state. The life span of the atoms in the excited state is about 10.sup.-8 sec, but there are also specific atoms which have a life span of the order of 1 to 10 msec. The latter atoms are slowly diffused throughout the electric discharge, collide with the structural material such as the barriers and the like and recombine. Then, the atoms disappear. The excited atoms with a long life expectancy are easily ionized when they collide with electrons, producing ionized electrons. Therefore, the greater the number of such excited atoms in the space, the more easily the ionization takes place. This stabilizes the discharge with the effect that the discharge voltage is reduced.
Also, the more space used for the discharge, the more advantageously the ionization takes place. Therefore, the discharge space has been expected to be increased by reducing the area per picture element.